The Koro Maru hot water bottle is a heat-retaining type that doesn't require hot water. It takes 10 minutes to heat up and can be used for 6-8 hours as a foot warmer inside a futon when used with a blanket. Perfect for the cold season. Easily rechargeable using an AC adapter. It's easy to warm up, making it recommended for those who feel cold easily. Product Name: Electric Hot Water Bottle Size: 27.5 x 18cm Weight: 1.1kg Temperature Gear: 65 degrees Celsius Power: 300W Only opened, and hardly used, it has been stored in the closet. This is a USED item, so I would appreciate it if those who understand this would purchase it. I do not smoke, and I do not have any pets.